Engine ignition control means



June 4,'194Y6. D. s. HERsL-:Y A 2,401,563

` ENGINE IGNITION-CONTROL, MEANS Filed Fb. 28, 1939 ATroRNEY l Patented June 4, `1946 ENGINE IGNITION CONTROL MEANS Donald S. Hersey, West Hartford, Conn., assigner to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application February 28', 1939, Serial No. 258,943

' l This invention relates to improvements in engine ignition control means and has for an object the provision of improved spark timing control means for preventing detonation of the explosive charges in the engine cylinders.

A further object resides in the provision of an improved engine ignition control means which is sensitive directly to detonation of the engine fuel chargesand is operative to maintain the engine spark timing just under the detonation point.

Other objects and advantages will be more par- In the drawing, Fig. 1 is a diagrammatic view of an arrangement of elements constructed and arranged according to the invention for the purpose indicated, and

Fig. 2 is a diagrammatic view of a modified form of a portion of the arrangement shown in y Fig. l.

Referring to the drawing in detail, the numeral III indicates an engine cylinder head to which is secured a cylinder barrel I2. A piston, not illustra-ted, is reciprocable in the cylinder barrel for converting the expansive force of fuel charges burned in the cylinder into mechanical energy. The fuel charge isignited in the combustion chamber by a timed electric spark when the piston is somewhere near its top dead center in a manner well known in the art of internal combustion engines. As is well known, when the degree of compression of the fuel charge at or immediately before exceeds the ability of the fuel to burn without detonation the phenomenon of knock or detonation occurs. Asthe nature, occurrence and eect of detonation have been thoroughly investigated and completely d e- 3 Claims. (Cl. 123-198) 2 I edied by delaying the ignition spark until the rate of pressure increase has been decreased to a, value at which the fuel will burn without detonation. This action detracts somewhat from the power developed by the engine soA that it is desirable to maintain the spark timing at the point of maximum advance consistent with non-detonating operation of the engine. As explained above it is among the purposes of this invention to provide a device which will maintain the spark' advance just under the detonating point.

The numeral I4 generally indicates a detonation sensitive device rigidly secured to the cylin. der head by suitable means such as the screw threaded stud I5. This device may conveniently comprise an outer casing I6 having an open end closed by a screw threaded cap I8 and containing an electric induction coil 20 surrounding amagnet 22 supported in space by springs 24 so that the magnet may move relative to the coil 20 when the casing I6 is suddenly moved. The springs 24 are-so designed in consideration of the mass of the magnet 22 that the natural vibration frequency of the spring supported magnet will be in resonance with thefrequency of vibration induced by detonation ofthe fuel in the combustion chamber of the engine. Thus, whenever the en gine detonatesl the magnet 22 will oscillate on its spring support and generate a small current in the coil 20. -This current is tapped at the terminals 26 and 28 and led to the remainder of the ignition controlling device. example the terminal 26, is connected with one segment 30 of a commutator generally indicated at 32 which has a separate segment for each or for selected cylinders of the engine. These segments are insulated from eachother and are contacted by a rotor 34 which is electrically connected with a condenser 36. The segments of the commutator 30 are preferably of such a. length that the rotor 84 is in contact with any'partic' ular segment substantially during the combustion period of the respective cylinder so that, if the magnet of the respective device is moved by vibration incident to valve action or other causes,

the circuit will at that time be open and no current will ilow.- Thus, the device will be sensitive to detonation induced vibrations only and will not be iniluencedby vibration due to other causes. The rotor 34 is mounted upon one end of a shaft schematically indicated by the line 38 which may be connected through a reduction gear 40 with a shaft 42 which drives the cam element 44 of the interrupter 48 which induces the ow of spark producing current. 'I'he shaft 42 is driven lfrom One` terminal, for

the engine through s mamme gear drive, as schematically indicated at ll, and the time relation of the spark to the position of the various engine parts is controlled by the operation of the interrupter by the cam Il. The interrupter may be moved relative to the cam to advance or retard the spark by 'rotation of the support ill upon which the interrupter is pivotally mounted As the current produced by the device Il is very small it is necessary to increase its value by some suitable amplifying device such as the thermionic relay tube, generally indicated at 52. The arrangement for this purpose may be in accordance with general practice in the radio and electric s industry, but as illustrated, the side of the condenser opposite the side connected with the rotor Il, is connected with the grid 5I oi the tube 5 2, and through a resistance or grid leak 58 and battery 5l with the line Il leading from the terminal 2l opposite the terminal 2l. The line 0n is connected with one side ci the iilament B2 which side o! the filament is also connected with one terminal of a filament heating battery B4 the other terminal of which is connected with the other side of the filament through the line IB and switch Il. The filament; l2 is connected with one terminal of the high potential battery 1li the other end of which is connected in parallel to a resistance I2 and a rectifier 1l. The plate 18 is connected to the side of the rectier opposite the side to which the battery 1l is connected, by the line 1I which includes a condenser lll located between the resistance 'l2 and the rectiiier 1l. The action of the tube l2 and rectiiier 14 is to convert the relatively small alternating current produced by the magnet 22 into a relatively large uni-direction current which is applied to the coil of the electro-magnet l2. 'Ihis electro-magnet controls a switch Il. in the arrangement shown in Fig. 1, connected into the tleld and rotor circuit oi a small reversible direct current series .motor Il energized by a suitable source oi electric current, such as the battery ll one side of which may be grounded through a suitable switch-ll. From the above description it is apparent that the motor I. will be energized whenever a detonation induced current is produced by the device Il. The motor It is connected by suitable speed reducing means, such as the worm 9| and gear 92, with an arm Il operatively connected with an arm Il on the rotatable support il so that operation of the motor acts to rotate the support ll to move the interruptor 4l relative to the cam Il in a direction to retard the timing of the ignition spark. The arm II is connected with the arm il by means of a loose connection, such as the ring Il and ring included pin Ill, to allow play for the angular displacement o! the arms ll and Il relative to each other and to avoid too sensitive an operation of the device, that is to render they device subject to response to a number of consecutive detonations rather than to a single isolated detonation which might happen without immediate recurrence in the operation of the enm- In the slightly modined form of the invention shown inFig. 2 the electro-magnet I2 acts on the armature Il! to which is connected to a .valve I" which controls the application ci hydraulic iiuid lunder pressure to the opposite sides of the piston III reciprocable in the cylinder Ill and having a rod Ill connectedwith the armv o! the rotatable support Il. Hydraulic duid under pressure high pressure line lil and may be conducted to or from the cylinder lll through the spaced ports lil and l I8. The arrangement is such that when one of the ports lil or Ill is connected by the valveill with the high pressure line lll the other port is connected by the same valve with the drain line |20.

With this arrangement the hydraulic motor devic'e shown in Fig. 2 serves the same purpose as the electric motor device shown in Fig. 1 to retard the timing of the ignition spark whenever a current is'generated by the device I4 being subiected to detonation induced vibration.

While two operative arrangements of an ignition controlling device constructed according to the invention have been hereinabove described and diagramatically illustrated in the accompanying drawing for the purpose of disclosing the invention, it is to be understood `that the invention is not limited to the particular arrangements so illustrated and described, but that such changes in the form and arrangement of the various elements may be resorted to as come within the scope of the subjoined claims.

Having now described the invention so that others skilled in the art may clearly understand the same, what it is desired to secure by Letters Patent is as follows:

l. An ignition timing control for an internal 'combustion engine comprising, a detonation sensitive device operative to generate a small electric current when subjected to detonation induced vibration, a commutator tor disconnecting said maybelcdtothevalvecasingIllthroughthe device during all of the engine cycle except the combustion period, and means actuated by said device i'or controlling the .timing of the ignition spark comprising an amplifier, a solenoid, and a motor actuated by said solenoid and operatively connected with the ignition mechanism of said engine.

v 2. In combination with an engine having one or more cylinders each having s,- combustion chamber equipped with electric ignition means, and an engine driven current interruptor for timing the ignition spark, means for automatically controlling the timing of said spark to avoid detonation in said cylinders comprising, a device operative to generate electric energy when subjected to detonation induced vibration secured to each cylinder or to each o! one or more selected cylinders, a hydraulic motor for changing the positions oi said interrupter, a solenoid valve ior controlling said motor, and an amplifying device between said generating device and said solenoid valve.`

3. In combination with an engine having one or more cylinders each having a combustion chamber equipped with electric ignition means, and an engine driven current interrupter for timing the ignition spark, means for automatically controlling the timing of said spark to avoid detonation in said cylinders comprising, devices operative to generate electric energy when subjectedto detonation induced Yvibration secured one to each of one or more of said cylinders, a commutator driven by said engine for rendering each generating device operative only during the combustion period of its respective cylinder, a motor for changing the position of said interrupter relative to said engine drive, a solenoid for controlling said motor, and an amplifying and rectifying electric circuit between said commutator and said motor.

DONALD s. maar. 

